A known example of a laminated polarizing plate is a circularly polarizing plate including a linearly polarizing plate and a retardation film placed thereon and having an in-plane retardation of ¼ wavelength (also referred to as “λ/4 plate”). For example, such a circularly polarizing plate is used in liquid crystal displays, organic electroluminescence (EL) displays, etc.
There are known various methods for manufacturing a circularly polarizing plate. For example, a known method includes forming a laminate of a linearly polarizing film and a λ/4 plate made of a piece of obliquely stretched polymer film to produce a circularly polarizing plate in the form of a roll (see for example Patent Document 1). Such a circularly polarizing plate can be continuously produced using rollers and thus can be produced with high productivity.
Unfortunately, the manufacturing method disclosed in Patent Document 1 involves bonding the linearly polarizing film and the λ/4 plate together with an adhesive or the like. At present, there is no known long laminated polarizing plate having a polarizing coating formed directly on a retardation plate such as a λ/4 plate or no known method for manufacturing such a long laminated polarizing plate.